1. Field of the Invention
The present invention relates to an image display device and a liquid crystal lens.
2. Description of the Related Art
Liquid crystal has such characteristics that it has fluidity like liquid, exhibits anisotropy in electrical and optical properties, and can be variously controlled in a molecule alignment state. Liquid crystal lenses have been known in which the liquid crystal having such properties is sealed in a pair of substrates and a distribution characteristic of the refractive index is controlled by controlling a voltage to be applied to a liquid crystal layer.
As the liquid crystal lenses, a liquid crystal lens that is in homogeneous alignment in a state where a voltage is not applied to the liquid crystal layer and is brought into a state of providing a lens effect by applying a voltage has been known. An image display device having the liquid crystal lens on a front surface of a display panel provides a viewer at a predetermined position with a two-dimensional image or a three-dimensional image.
JP 2011-164273 A intends to provide a liquid crystal display device in which a steep change in light transmittance with respect to an applied voltage is improved. JP 2011-164273 A discloses a liquid crystal display device in which a twist direction of a liquid crystal material determined by the combination of a pretilt angle and alignment treatment directions of a set of alignment films is opposite to a twist direction of the liquid crystal material induced by a chiral agent.